Stihl MS 661

66 MS 661, MS 661 C-M
Checking wires between
solenoid valve unit and
diagnostic socket
– Connect test cable, b 8.3.2
: Pull connector (1) off the solenoid
valve (2).
: Measure resistance between red
wire (1) on the solenoid valve's
connector and test cable's black
plug (2).
Specified value: < 10 Ω
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: Measure resistance between
black wire (1) on the solenoid
valve's connector and test
cable's red plug (2).
Specified value: < 10 Ω
If the specified values are not
obtained
– Check contact faces on the plug
and connector tag, and wires for
break, or contact between cable
lug / terminal socket, replace
switch unit if necessary, b 8.5
– Reassemble all other parts in the
reverse sequence.
8.4 Wiring Harness
The wires of the M-Tronic and the
short circuit wire are combined in a
wiring harness. Removal and
installation are described in the
chapter on "Wiring Harness with M-
Tronic / Heating, Removing and
Installing, b 7.10.
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8.5 Switch Unit
– Remove the filter base, b 13.3
– Test the switch unit, b 8.3.5
– Remove the carburetor, b 13.4
: Remove the connector (1) from
the solenoid valve (2) – do not
tug wires to remove the
connector.
: Take out the screws (1) and
remove the switch unit (2).
: Check lever on choke shaft (3),
replace if necessary, b 13.5.7
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